Younan Xia

Bio: Younan Xia is an academic researcher from The Wallace H. Coulter Department of Biomedical Engineering. The author has contributed to research in topics: Nanocages & Nanowire. The author has an hindex of 216, co-authored 943 publications receiving 175757 citations. Previous affiliations of Younan Xia include Washington University in St. Louis & University of Texas at Dallas.

On-chip screening of experimental conditions for the synthesis of noble-metal nanostructures with different morphologies

Abstract: The applications of nanostructures critically depend on their morphologies. Although significant progress has been made in the chemical synthesis of nanostructures with a variety of different morphologies, it is still highly desired to develop an approach that allows one to quickly identify the best set of parameters for nanostructure syntheses. Herein, an on-chip approach to the rapid screening of experimental conditions pivotal to the production of nanostructures with different morphologies is reported. The key component of this approach is an array of reactors containing solutions with a one- or two-dimensional gradient in reagent concentration, pH value, or reaction temperature. In the proof-of-concept experiments, the parameters needed for the production of Au and Pd nanostructures with various morphologies are quickly identified. In principle, this approach can be extended to other systems for rapid screening and optimization of experimental conditions involved in the syntheses of different types of nanostructures.

Promoting the Outgrowth of Neurites on Electrospun Microfibers by Functionalization with Electrosprayed Microparticles of Fatty Acids.

Abstract: Controlling the outgrowth of neurites is important for enhancing the repair of injured nerves and understanding the development of nervous systems. Herein we report a simple strategy for enhancing the outgrowth of neurites through a unique integration of topographical guidance and a chemical cue. We use electrospray to easily functionalize the surface of a substrate with microparticles of natural fatty acids at a controllable density. Through a synergistic effect from the surface roughness arising from the microparticles and the chemical cue offered by the fatty acids, the outgrowth of neurites from PC12 cells is greatly enhanced. We also functionalize the surfaces of uniaxially aligned, electrospun microfibers with the microparticles and further demonstrate that the substrates can guide and enhance directional outgrowth of neurites from both PC12 multicellular spheroids and chick embryonic dorsal root ganglia bodies.

Dual-oxide sinter resistant catalyst

Abstract: A catalyst material for use at elevated temperatures is provided. The material can include a plurality of fibers and a plurality of particles supported on the fibers. In addition, a porous layer can cover the plurality of particles and allow for process fluid to come into contact with the particles, and yet retard sintering of the particles at elevated temperatures is present. The plurality of fibers can be a plurality of nanofibers which may or may not be oxide nanofibers. The particles can be metallic nanoparticles and the porous layer can be a porous oxide layer.

Noble‐Metal Nanocrystals with Concave Surfaces: Synthesis and Applications

Abstract: Metal nanocrystals with concave surfaces are interesting for a wide variety of applications that are related to catalysis, plasmonics, and surface-enhanced spectroscopy. This interest arises from their high-index facets, surface cavities, and sharp corners/edges. Two major challenges are associated with this novel class of nanocrystals: 1) how to generate a concave surface with negative curvature, which is not favored by thermodynamics owing to its higher energy than the convex counterpart; and 2) how to stabilize the morphology of a nanocrystal with concave structures on the surface. Recently, a number of different procedures have been developed for the synthesis of noble-metal nanocrystals with concave surfaces. This Review provides a brief account of these developments, with the aim of offering new insights into the growth mechanisms. We focus on methods based on two general strategies: 1) site-specific dissolution through etching and galvanic replacement; and 2) directionally controlled overgrowth by facet-selective capping, kinetic control, and template-directed epitaxy. Their enhanced catalytic and electrocatalytic properties are also described.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346